Graft copolymers containing fluoroaliphatic groups

ABSTRACT

A fluorochemical graft copolymer comprising: a base polymer comprising polymerized units derived from monomers having terminal olefinic double bonds, having a moiety comprising a fluoroaliphatic group grafted thereto. Also disclosed are processes for preparing such fluorochemical graft copolymers, forming and annealing methods for enhancing the surface activity of such a graft copolymer, polymer blends comprising such a fluorochemical graft copolymer and a matrix polymer that is miscible with the base polymer, and a method for reducing the surface energy of a polymer comprising polymerized units derived from monomers having terminal olefinic double bonds.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to continuous processes using wiped-surfacereactors for free radical graft polymerization of polyolefins, and tograft copolymers thereby produced. In another aspect, this inventionrelates to polymerizable olefins containing fluoroaliphatic groups, andcopolymers thereof.

2. Description of the Related Art

Processing or production of polymeric resins using wiped-surfacereactors such as screw extruders and twin screw extruders is well known(such processing is often called reactive extrusion). Twin screwextruders and their use in continuous processes such as graftpolymerization, alloying, bulk polymerization of vinyl monomers, andcondensation and addition reactions are generally described in PlasticsCompounding Jan./Feb. 1986, pp. 44-53 (Eise et al.) and PlasticsCompounding, Sept./Oct. 1986, pp. 24-39 (Frund et al.). Graft reactionsare said to be carried out by first melting a polymeric species in theinitial stages of an extruder, injecting a peroxide catalyst into theextruder, and mixing in a monomer under high shear conditions.Advantages of the twin screw extrusion process are said to includenarrow distribution of molecular weight, improved melt-flow properties,consistent process control, and continuous processing.

Graft polymerization reactions of polyolefins with various monomersusing wiped-surface reactors are known. Such grafting is said to beuseful in providing a polymer adduct with functionality to allow furthermodification of structure and properties. General mechanistic proposalsregarding formation of these "mechanochemically synthesized" adducts arediscussed in connection with grafting of maleic anhydride ontopolypropylene in Polymer Prep., 1986, 27, 89 (Al-Malaika).

A number of particular free radical graft polymerization reactions havebeen reported. For example, U.S. Pat. No. 3,177,270 (Jones et al.)discloses a process for preparing graft copolymers by mixing an olefinpolymer at a temperature between 110° C. and 250° C. while contactingthe polymer with a minor proportion of a mixture comprising a monovinylaromatic compound and optionally one or more other monomers such asacrylic acid, methacrylic acid, acrylonitrile, methyl methacrylate,methacrylonitrile, or maleic anhydride, the mixture having dissolvedtherein an organic peroxide.

British Pat. No. 1,292,693 (Steinkamp et al.) discloses use of asingle-screw extruder to graft monomers such as maleic anhydride andacrylic acid onto polyolefins such as polypropylene in the presence of asuitable free radical initiator such as an organic peroxide. The productgraft copolymers are said to have a melt flow rate (MFR) of at least 50%greater than the MFR of the base polymer.

U.S Pat. No. 4,003,874 (Ide et al.) discloses modified polyolefinsobtained by adding an unsaturated carboxylic acid or an anhydridethereof and an organic peroxide to a polyolefin and melting thesecomponents in an extruder. The polyolefin so obtained is said to adhereto glass fibers.

U.S. Pat. No. 4,146,529 (Yamamoto et al.) discloses a process forproduction of modified polyolefins by combining a polyolefin with one ormore carboxylic acids or their anhydrides in an extruder in the presenceof a radical producing agent and an organosilane.

U.S. Pat No. 4,228,255 (Fujimoto et al.) discloses a method forcrosslinking a polyolefin, the polyolefin being a low densitypolyethylene or a polyolefin mixture containing a low densitypolyethylene, comprising reacting the polyolefin with an organic silaneand an organic free radical initiator to form a silane-graftedpolyolefin, then mixing the silane-grafted polyolefin with a silanolcondensation catalyst. The mixture is extruded with heating in asingle-screw extruder to provide a crosslinked polyethylene.

SUMMARY OF THE INVENTION

This invention provides a fluorochemical graft copolymer comprising: abase polymer comprising polymerized units derived from monomers havingterminal olefinic double bonds, having a moiety comprising afluoroaliphatic group grafted thereto. The grafted fluoroaliphatic groupis generally derived from a fluorochemical olefin comprising afluoroaliphatic group and a polymerizable double bond.

The fluoroaliphatic group of the fluorochemical olefin is generallybonded to the polymerizable double bond through a linking group. Suchfluorochemical olefins can be represented by Formula I below:

    (R.sub.f).sub.a Q(CR═CH.sub.2).sub.b                   I

R is hydrogen, trifluoromethyl, or straight chain or branched chainalkyl containing 1 to about 4 carbon atoms;

a is an integer from 1 to about 10;

b is an integer from 1 to about 6;

Q is an (a+b)-valent linking group that does not substantially interferewith free radical polymerization; and

R_(f) is a fluoroaliphatic group comprising a fully fluorinated terminalgroup containing at least seven fluorine atoms.

This invention also provides a process for preparing the fluorochemicalgraft copolymers described above, which process comprises the steps of

(1) feeding to a reactor materials comprising

(a) a base polymer comprising polymerized units derived from monomershaving terminal olefinic double bonds;

(b) an effective amount of a free radical initiator system comprisingone or more free radical initiators; and

(c) a fluorochemical olefin as described above, wherein all materialsare substantially free of oxygen;

(2) reacting the materials in the reactor to provide a graft copolymer;and

(3) withdrawing the graft copolymer from the reactor.

Preferably, the base polymer is fed to the reactor in a region of thereactor preceding or coincident with the region in which the initiatorsystem is fed and the fluorochemical olefin is fed to the reactor in aregion of the reactor subsequent to the region in which the initiator isfed.

A preferred embodiment of the process of the invention involves use of aleast two free radical initiators to maximize the number of graftedfluorochemical moieties. Desired thermoplastic, melt-flow, and lowsurface energy properties of the resultant graft copolymer can thus beoptimized.

In another aspect, this invention provides methods of enhancing thesurface activity of a fluorochemical graft copolymer film. One suchmethod is an annealing method comprising the steps of:

a) providing a surface comprising a fluorochemical graft copolymer asdescribed above, and

b) annealing the surface by heating it at a temperature and for a timeeffective to increase the amount of the grafted fluorochemical at thesurface

This invention also provides a forming method for controlling the amountof grafted fluorochemical at the surface of a composition comprising agraft copolymer of the invention, comprising the steps of

(1) selecting a surface that is made of a material that will control theamount of grafted fluorochemical at the surface of the composition; and

(2) forming the composition against the surface selected in step (1).

This invention also provides polymer blends comprising a fluorochemicalgraft copolymer as described above and a matrix polymer that is misciblewith the base polymer of the graft copolymer.

Further, this invention provides a method for reducing the surfaceenergy of a polymer, comprising the step of grafting to said polymer afluorochemical olefin comprising a fluoroaliphatic group and apolymerizable double bond.

Relatively little fluorochemical olefin is required for the preparationof the graft copolymers of the invention, and the forming and annealingmethods further reduce the amount of fluorochemical needed for aparticular application.

Graft copolymers of the invention have lower surface energies than thecorresponding base polymers, and they exhibit desirable thermoplastic,melt flow, and release properties. Moreover, these graft copolymers areuseful in applications where oil repellency and solvent resistance aredesirable.

BRIEF DESCRIPTION OF THE DRAWING

The Drawing is represented by FIGS. 1-3.

FIG. 1 is an exemplary flow diagram of the process of the invention.Ancillary equipment such as pumps and valves, has not been illustrated,and secondary process streams such as utility lines (e.g., coolingwater) have been omitted.

FIG. 2 is a flow diagram of a counter-rotating twin screw extruderuseful in this invention.

FIG. 3 is a flow diagram of another counter-rotating twin screw extruderuseful in the process of this invention.

DETAILED DESCRIPTION OF THE INVENTION

A fluorochemical graft copolymer of the invention comprises a basepolymer having a moiety comprising a fluoroaliphatic group graftedthereto. Generally a plurality of the grafted moiety is present in agraft copolymer of the invention.

The fluoroaliphatic group is generally derived from a fluorochemicalolefin comprising a fluoroaliphatic group and a polymerizable doublebond. The grafting occurs through the polymerizable double bond. Thedouble bond is of course not present in the product graft copolymer ofthe invention; rather, in the grafting process the double bond becomes asaturated link between the base polymer and the fluoroaliphatic group.In the instant specification and claims a reference to a fluoroaliphaticgroup grafted through a double bond designates the presence of such asaturated link and does not designate the presence of olefinicunsaturation in the grafted moiety as it is incorporated in the graftcopolymer.

Suitable base polymers include polymers comprising polymerized unitsderived from monomers having terminal olefinic double bonds. This classof polymers is known to those skilled in the art and includes polymerssuch as polymethyl methacrylate, poly-4-methylpentene, polypropylene,polybutylene, polystyrene, polyethylene, polybutadiene, and copolymerssuch as ethylene/vinyl acetate copolymer and ethylene/butyl acrylatecopolymer, and the like, and mixtures and blends thereof. Such polymersof any molecular weight are suitable. Polymers with a wide range of meltindex values (e.g., from about 0.1 to about 500) are suitable. Meltindex values are determined by the American Society for TestingMaterials method ASTM D-1238. Due to their relatively low viscosity andability to diffuse to the surface of a polymer blend, low molecularweight polyolefins, preferably with melt indices of at least about 20,(e.g., low molecular weight polyethylene and polypropylene), and up toabout 500 are particularly useful as base polymers for graft copolymersof the invention that are intended for use in the polymer blends of theinvention (described in detail below).

Fluorochemicals that can be grafted to the base polymer include knownfluorochemical olefins that comprise a fluoroaliphatic group and apolymerizable double bond. Fluorochemical olefins suitable for use inthe invention include those disclosed in, for example, U.S. Pat. Nos.2,642,416 (Ahlbrecht et al.), 2,803,615 (Ahlbrecht et al.), 2,841,573(Ahlbrecht et al.), 3,102,103 (Ahlbrecht et al.), 3,282,905 (Fasick etal.), 3,304,278 (Hauptschein et al.), 3,378,609 (Fasick et al.),3,384,627 (Anello et al.), 3,386,977 (Kleiner), 3,392,046 (Marder),3,407,183 (Farah et al.), 3,514,420 (Katsushima et al.), 3,532,659(Hager et al.), 3,544,663 (Hauptschein et al.), 3,546,187 (Tandy),3,547,861 (Anello et al.), and 3,578,487 (Knell et al.), the disclosuresof which are incorporated herein by reference. The list above isintended to be merely exemplary and not exhaustive of patents disclosingsuitable fluorochemical olefins. Generally, suitable fluorochemicalolefins comprise a fluoroaliphatic group bonded through a linking groupto a polymerizable double bond and can be represented by the generalFormula I below:

    (R.sub.f).sub.a Q(CR═CH.sub.2).sub.b                   I

wherein a, b, R, R_(f) and Q are as defined above.

In a compound of Formula I, a and b are integers representing the numberof fluoroaliphatic groups and the number of olefinic groups,respectively, in the fluorochemical olefin. The value of a can be 1 toabout 10, preferably 1 to about 6, more preferably 1 to about 3, andmost preferably 1. The value of b can be 1 to about 6, preferably 1 toabout 3, and more preferably 1. R in a compound of Formula I ishydrogen, trifluoromethyl, or lower alkyl (i.e., straight chain orbranched chain alkyl of 1 to about 4 carbon atoms).

Q is an (a+b)-valent organic moiety that can have a wide variety ofstructures, for example, alkylene, e.g., methylene, ethylene,cyclohexylene, arylene, e.g., phenylene, and combinations thereof, e.g.xylylene, or combination of such moieties with suchheteroatom-containing moieties as oxy, thio, aza, carbonyl, sulfonyl,sulfoxy, sulfonamido, carboxamido, urylene, carbamato, and imino, andcombinations thereof such as sulfonamidoalkylene, carboxamidoalkylene,oxydialkylene, alkylenecarbamato and the like. The particular structureof Q for a particular fluorochemical olefin is not unduly critical tothis invention. Q can therefore be selected by virtue of ease ofpreparation and, for example, commercial availability of thefluorochemical olefin or the particular reactants used in preparing thefluorochemical olefin.

R_(f) is a fluoroaliphatic group that is a fluorinated, stable, inert,non-polar, preferably saturated, and both hydrophobic and oleophobic.R_(f) can be straight chain, branched chain, or, if sufficiently large,cyclic, or a combination thereof, such as alkylcycloalkyl. Thefluoroaliphatic group can also include catenary oxygen, sulfur, ornitrogen. Generally R_(f) will have 3 to about 20 carbons atoms,preferably 6 to about 12 carbon atoms, and will contain about 40 toabout 78 weight percent, preferably about 50 to about 78 weight percent,carbon-bound fluorine. The terminal portion of the R_(f) group is fullyfluorinated and contains at least 7 fluorine atoms. Exemplary terminalportions include --CF₂ CF₂ CF₃, --CF(CF₃)₂, --CF₂ SF₅, and the like.Preferred R_(f) groups are fully or substantially fully fluorinated, asin the case where R_(f) is perfluoroalkyl (i.e., C_(n) F_(2n+1)).

Several particular exemplary compounds of Formula I are shown below:##STR1##

In a preferred embodiment, the graft copolymer comprises a polymericbackbone comprising polymerized units derived from monomers havingterminal olefinic double bonds, having bonded thereto a moiety of theformula

    --CH.sub.2 --CHR--Q--R.sub.f

wherein Q is a divalent linking group that does not substantiallyinterfere with free radical polymerization, and R and R_(f) are asdefined above.

Preferably a graft copolymer of the invention comprises about 0.1% toabout 20%, more preferably 0.5 to about 10% by weight of graftedfluorochemical olefin. In a process of the invention as described belowit is preferred to use like quantities of fluorochemical olefin, i.e.,about 0.1 to about 20% or more by weight, more preferably 0.5 to about10% weight based on the weight of the base polymer.

In a process of the invention, the base polymer and a fluorochemicalolefin are reacted in the presence of an initiator system comprising oneor more free radical initiators to provide a fluorochemical graftcopolymer. The initiator system serves to initiate free radical graftingof the fluorochemical olefin onto the base polymer.

Many initiators are known. Suitable initiators include: hydroperoxidessuch as cumene, t-butyl, and t-amyl hydroperoxides, and2,5-dihydroperoxy-2,5-dimethylhexane; dialkyl peroxides such asdi-t-butyl, dicumyl, and t-butyl cumyl peroxides,2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and2,5-dimethyl-2,5-di(t-butylperoxy)hex-3-yne; peroxyesters such ast-butyl perbenzoate and di-t-butyl-diperoxy phthalate, diacyl peroxidessuch as benzoyl peroxide and lauroyl peroxide; peroxyketals such asn-butyl-4,4-bis(t-butylperoxy)valerate and1,1,-di-t-butylperoxy-3,3,5-trimethylcyclohexane; and azo compounds suchas azoisobutyronitrile.

Reaction conditions under which a graft copolymer of the invention canbe prepared typically involve heating at about 150° C. to about 250° C.Reactants typically have a residence time of about 1 to 20 min. It istherefore difficult to select a single initiator with a decompositionrate such that initiating radicals will be present in a substantialconcentration for a prolonged period of time when a low concentration ofinitiator is used. It is therefore preferred to use a mixture of atleast two initiators as an initiator system. Proper selection of thecomponents of the initiator system overcomes the above-discusseddifficulty with single initiators, and allows control and optimizationof the physical properties of the product graft copolymer.

Generally it is preferred that each initiator in an initiator systemhave a rate of decomposition substantially different from those of theother initiators in the initiator system. For example, in a process witha residence time of about 5-10 minutes at a temperature of about 200°C., an initiator system wherein one initiator has a half-life of about30 seconds and the other initiator has a half-life of about 2 minuteshas been found suitable.

Preferred initiator systems include mixtures comprising from about 40%to about 60% by weight of 2,5-dimethyl-2,5-di(t-butylperoxy) hexane,(such as that commercially available as LUPERSOL™ 101 from PennwaltCorporation) and from about 60% to about 40% by weight of an initiatorsuch as 2,5-dimethyl-2,5-di(t-butylperoxy) (such as that commerciallyavailable as LUPERSOL™ 130, Pennwalt Corporation), t-butylhydroperoxide,or di-t-butylperoxide. Initiator decomposition rates are temperaturedependent, and other particular initiator systems and preferredconcentrations thereof can be selected by those skilled in the artconsistent with the temperature of the reaction and the residence timeof the reactants.

Total initiator concentration in a process of the invention ispreferably from about 0.1% to about 1%, more preferably from about 0.25%to about 0.5% based on the weight of the base polymer.

Fluorochemical graft copolymers of the invention can be prepared usingvarious well known reactors such as stirred tank reactors, tubularreactors, and extruders. Graft copolymers are preferably made by aprocess involving a wiped-surface reactor. A wiped surface reactorcomprises a shell or vessel that contains at least one rotor having awiping portion located close to the inside surface of the shell and aroot portion spaced further from the shell than the wiping portion. Asthe rotor is rotated, the wiping portion passes close enough to theinside surface of the shell to clean the surface and form a seal whenthe reactor contains monomer and/or polymer but not so close as to causepermanent deformation of either the rotor or shell. It is necessary thatthe root surface of the rotor also be wiped or cleaned continuouslyduring the operation of the reactor.

Intermeshing twin screw extruders can be used as wiped surface reactors.The screws function as the rotor and the flight lands function as thewiping portion, while the screw root surface between the flight landsfunctions as the root surface. Clearances between the inside of thebarrel wall of the extruder and the flight lands of the screws arepreferably from about 0.25 to 0.5 mm. Although co-rotating twin screwextruders can be used, counter-rotating twin screw extruders arepreferred. The counter-rotating extruder acts as a positive displacementpump conveying the reactant stream, and it also behaves as a series ofsmall mixing zones or continuous stirred tank reactors. Thecounter-rotating twin screw extruder also gives good control overmelting, mixing, and reaction temperatures.

Preferably, screws of a counter-rotating twin screw extruder are dividedinto segments, i.e., extruder screws can be composed of a number ofseparate screw segments that fit onto a common drive shaft by a keywayand can be disassembled and rearranged in various orders andconfigurations. It is also possible to use screw segments havingmultiple (e.g., two or three) starts and various pitch, and one or morescrew segments can be reversed to increase mixing. Residence time of thereactants, and properties of the resultant product, can therefore bevaried by selection of screw pitch and/or screw speed (i.e., screw rpm).Furthermore, each particular zone of a twin screw extruder can beindependently heated or cooled by external heating or cooling means,allowing further control of reaction conditions.

Use of a wiped surface reactor in the invention is discussed referringto FIG. 1. A base polymer can be fed in a region of the reactorcoincident with the region in which the initiator system is fed. Forexample, the desired base polymer, preferably in pellet form, can bewetted with a free radical initiator system and purged with an inert gassuch as nitrogen, helium, argon or the like, to render the materialsubstantially free of oxygen (i.e., oxygen, if present, is present in anamount such that it does not significantly affect the desired freeradical polymerization reactions). This material can be fed at apredetermined rate into feed zone 1 of the wiped surface reactor. It ispreferred, however, to feed the base polymer in a region of the reactorpreceding the region in which the initiator system is fed. Feed zone 1typically comprises a feed throat, into which base polymer can be fedinto the upstream end, and into which the initiator system can be fed atthe downstream end.

A further alternate method of feeding the base polymer and the initiatorinvolves use of a 2-component feed zone consisting of a base polymerfeed zone into which base polymer is fed, followed in sequence by aseparate initiator feed zone into which the initiator is fed. Theextruder is preferably starve fed, i.e., all material fed into the feedzone is conveyed into initiator/melt zone 2 of the extruder, and nothingis held up in feed zone 1.

Feed rates can vary with the size of the reactor and for any given sizeof reactor, one skilled in the art will be able to determine suitablefeed rates. As an example, when a 34 mm counter-rotating twin screwextruder is used, feed rates are preferably from about 0.4 Kg/h to about9 Kg/h. The feed zone screw preferably has a high pitch (e.g., 20 mm) toaccommodate base polymer pellets The feed zone can, if desired, beoperated in a temperature controlled manner, depending on the reactants,reaction conditions and the like. Generally, it is suitable to maintainthe feed zone of the extruder in a temperature range from about 10° C.to about 50° C., depending on the base polymer used.

In initiation/melt zone 2, the initiator system and base polymer aremixed and heated to initiate radical chain reactions. Preferredtemperatures will depend on the particular base polymer and initiatorsystem, but generally temperatures in the range between 150° C. andabout 250° C. are suitable.

In monomer addition zone 3, a nitrogen-purged fluorochemical olefin isadded, usually by a high pressure pump and under an inert atmosphere.The fluorochemical olefin is generally fed as a liquid or as a solutionin an inert solvent (e.g., decane, toluene, tetrahydrofuran or the like.Preferred feed rates are variable, and when a LEISTRITZ™ 34 mmcounter-rotating twin screw extruder is used, feed rate is preferablyabout 4 g/h to about 180 g/h. It is preferred to maintain the monomeraddition zone at a temperature of about 150° C. to about 250° C.

Grafting proceeds in reaction zone 4. The reaction zone is heated. Aswith the initiator/melt zone, the preferred temperature will depend onthe particular base polymer and initiator system used. Further, thepreferred temperature of the reaction zone will depend on the particularbase polymer and initiator system used and on the intended residencetime in the reaction zone Generally, temperature in the range of 150° C.to 250° C. and residence times in the range of 1 minute to about 10minutes are suitable.

In reactions where residual solvent or monomer remains, it is preferredto remove it from the grafted product by venting. This can be done indevolatilization zone 5, where a vacuum (e.g., about 10 kPa absolutepressure) can be applied to a vent line. The resultant product is thenpassed through block zone 6, which conveys the product graft copolymerfor any further processing as desired, e.g., shaping in a die, quenchingin a suitable quenching liquid, or pelletizing for convenience ofhandling and/or storage.

The graft copolymers of the invention can find application where goodrelease properties, oil repellency, water repellency, solventresistance, and other properties of fluorochemicals are advantageous.

The amount of grafted fluorochemical at the surface (i.e., the surfacefluorochemical density) of a composition comprising a graft copolymer ofthe invention can be increased by the annealing method of the invention.In such a method, a graft copolymer or a film thereof is annealed at atemperature and for a time effective to increase the amount of graftedfluorochemical at the surface. Effective temperature and time will bearan inverse relationship to one another and a wide range of conditionswill be suitable. Generally, annealing at a temperature between about50° C. and about 160° C. for a period of several minutes to severalhours provides a composition with an increased amount of graftedfluorochemical at the surface. Annealing apparently allows thefluorochemical in the graft copolymer to migrate to the surface with aresultant increase in surface activity, improved release properties, andimproved oil and water repellency and solvent resistance.

The annealing method, by increasing surface fluorochemical density, canalso serve to minimize the amount of grafted fluorochemical olefin thatmust be present in a graft copolymer of the invention for a particularapplication.

Another method of controlling the surface fluorochemical density of acomposition comprising a graft copolymer of the invention is a formingmethod, wherein the composition is formed (e.g., as during molding orduring pressing into a film) against a selected forming surface. Theeffect of the selected forming surface on surface fluorochemical densityis as follows: Generally, surface fluorochemical density is greater whena composition is formed against a fluorochemical surface, e.g.,polytetrafluoroethylene (PTFE, TEFLON™ polytetrafluoroethylene, DuPont)or a surface made of a graft copolymer of the invention, than when it isformed against a polyimide surface (e.g., KAPTON™ polyimide, DuPont).Forming against a chrome surface results in a lower surfacefluorochemical density than forming against eitherpolytetrafluoroethylene or polyimide. Through the use of a formingsurface having several distinct regions, each of an independentlyselected material, the forming method of the invention can be used toprovide a surface with regionally controlled surface fluorochemicaldensity and hence regionally controlled release properties, oilrepellency, and solvent resistance. Further, since the forming methodcan increase surface fluorochemical density, it can be used to minimizethe amount of grafted fluorochemical olefin that must be present in agraft copolymer of the invention for a particular application.

A graft copolymer of the invention can be blended with a matrix polymerthat is miscible with the base polymer of the graft copolymer in orderto form a polymer blend. The base polymer itself is of course a suitablematrix polymer for use in a polymer blend of the invention. Furthermore,compilations of polymer miscibility data are commonly available.Therefore, suitable matrix polymers, i.e., those that are miscible withthe particular base polymer, can be easily selected by those skilled inthe art. In a polymer blend of the invention the fluorochemical graftcopolymer serves as a fluorochemical additive that imparts improvedrelease properties to the matrix polymer. Also, the physical properties(e.g., viscosity, impact strength) of the graft copolymer can beimproved by the matrix polymer. Further, the tendency of the graftcopolymer to become "physically crosslinked" with the miscible matrixpolymer causes the properties imparted by the fluoroaliphatic groups tobe more durable than those imparted by a monomeric fluorochemicaladditive.

A polymer blend of the invention comprises a fluorochemical graftcopolymer of the invention in an amount sufficient to impart to theblend the release properties of the fluorochemical graft copolymer. Theamount of fluorochemical graft copolymer that constitutes a sufficientamount will vary with the fluorine content of the graft copolymer, andthe preferred amount will vary according to the intended use of thepolymer blend, Generally, a polymer blend of the invention preferablycomprises at least about 1 percent, more preferably at least about 10percent, and most preferably at least about 30 percent by weight ofgraft copolymer based on the weight of the matrix polymer.

Objects, features, and advantages of this invention are furtherillustrated by the following examples. The particular materials andamounts thereof recited in these examples, as well as other conditionsand details, should not be construed to unduly limit this invention.

In the following examples all parts and percentages are by weight unlessotherwise specified and all temperatures are in degrees Celsius unlessotherwise indicated.

EXAMPLES EXAMPLE 1-9

Polypropylene resin base polymer (DYPRO™ 8771 pellets, melt index: 9,commercially available from Fina Co., Houston, Tex.) was mixed in a5-gallon shaker with 0.25% by weight of 90% liquid2,5-dimethyl-2,5-di(t-butylperoxy)hexane (LUPERSOL™ 101, PennwaltCorporation, Philadelphia, Pa.) and 0.25% by weight of one of thefollowing: (a) 90-95% 2,5-dimethyl-2,5-di(t-butylperoxy)hex-3-yne(LUPERSOL™ 130, Pennwalt); (b) 90% liquid 5-butyl hydroperoxide(LUPERSOL™ 90, Pennwalt); (c) 98.5% liquid di-t-butyl peroxide(Pennwalt).

The base polymer/initiator mixture was then purged with nitrogen for 30minutes. The resin in the feed hopper and in the feed zone of theextruder was kept under nitrogen purge and the base polymer/initiatormixture was fed with an augered feed means into the feed zone of a 34 mmcounter-otating LEISTRITZ™ (LEISTRlTZ LSM 30.34 GG, Nurenburg, Germany)twin-screw extruder (length to diameter, L/D=35:1) configured asdescribed below with reference to FIG. 2.

FIG. 2 shows a twin-screw extruder with a feed hopper 10, feed zone 12,and a heated barrel that comprises: an initiation/melt zone comprisingbarrel section 14; a reaction zone comprising a monomer feed zone(barrel section 16) and barrel sections 18, 20, 22, 24, and 26; adevolatilization zone comprising barrel section 28; and a block zonecomprising barrel sections 30 and 32. Each barrel section is 120 mmlong, and the extruder has a total length of 1200 mm.

Transducer ports (e.g., T4 represents transducer number 4 located inbarrel section 24) are located at 30 mm, and/or 90 mm into each heatedbarrel section. Thermocouple ports are located at 60 mm into each heatedbarrel section. Melt temperatures of 180° C., 200° C., and 220° C. wereused with each initiator system. Polymer/initiator flow rate was kept atabout 40-50 g/min. N-butyl perfluorooctanesulfonamidoethyl acrylate(BuFOSEA) was purged with nitrogen and added to a nitrogen-purgeddisplacement pump, and added in heated barrel section 16, 270 mm fromthe start of the screws, at a rate of 1 mL/min. Heated barrel section 28was vented under vacuum. Product graft copolymers were conveyed from theblock zone (barrel sections 30 and 32), which was maintained at 180° C.,into a water bath and fed into a pelletizer to afford generallycylindrical beads of 3 to 4 mm in length and a diameter of about 1 mm.Reaction conditions are summarized in TABLE 1, wherein L101 designatesLUPERSOL™ 101 initiator, L130 designates LUPERSOL™ 130 initiator, TBHPdesignates t-butyl-hydroperoxide, and DTBP designates di-t-butylperoxide.

                  TABLE 1                                                         ______________________________________                                                                        Polymer                                                Melt        Initiator  Flow Rate                                     Example  Temp (°)                                                                           Mixture    (g/min)                                       ______________________________________                                        1        180         L101/L130  48.7                                          2        200         L101/L130  45.0                                          3        220         L101/L130  41.4                                          4        180         L101/TBHP  46.4                                          5        200         L101/TBHP  44.4                                          6        220         L101/TBHP  44.0                                          7        180         L101/DTBP  44.0                                          8        200         L101/DTBP  43.0                                          9        220         L101/DTBP  35.0                                          ______________________________________                                    

Grafting was confirmed by two methods. In the first method, samples inTABLE 1 were extracted in boiling tetrahydrofuran (THF) in aconventional extraction apparatus until a stable weight loss wasreached. The polymer was analyzed by infrared spectroscopy before andafter extraction. Grafting was confirmed by the presence of strongabsorption band at 1720 cm⁻¹ after extraction, which corresponds to thecarbonyl absorbance of the acrylate moiety.

Samples of the graft copolymers with thickness of about 0.13 mm weremade by pressing (at a pressure of about 41.4 kPa for 30 seconds using aWABASH™ heated press, Wabash Co., Wabash, Ind.) about 10 g of the graftcopolymers between chrome-coated aluminum plates at about 200° C.Pressed samples were quenched from the molten state to the solid statein a room temperature water bath. Hexadecane contact angle measurementswere made on these films and on polypropylene base polymer controlsample using the sessile drop method as described by A. W. Newman and R.J. Good in "Techniques for Measuring Contact Angles," Surface andColloid Science, 11, Plenum Press, N.Y., 1979. Results are shown inTABLE 2.

                  TABLE 2                                                         ______________________________________                                        Example      Contact Angle (°)                                         ______________________________________                                        PP Control   0                                                                PTFE         47 ± 1                                                        1            22 ± 3                                                        2            19 ± 3                                                        3            20 ± 2                                                        4            23 ± 3                                                        5            21 ± 3                                                        6            15 ± 2                                                        7            20 ± 3                                                        8            19 ± 4                                                        9            20 ± 2                                                        ______________________________________                                    

The results in TABLE 2 show improved surface activity, compared to apolypropylene (PP) control, for all Examples.

Electron spectroscopy for chemical analysis (ESCA) measurements werealso done to confirm grafting Fluorine to carbon (F:C) ratios forExamples 1 and 4 are listed in TABLE 3 below.

                  TABLE 3                                                         ______________________________________                                        Example        Composition F:C                                                ______________________________________                                        Control        PP          0                                                  1              PP/BuFOSEA  0.25                                               4              PP/BuFOSEA  0.31                                               ______________________________________                                    

TABLE 4 below compares surface energy values determined for films ofpolypropylene, polytetrafluoroethylene (PTFE), and the graft copolymerof Example 2.

                  TABLE 4                                                         ______________________________________                                        Polymer Sample  Surface Energy (Dyne/cm)                                      ______________________________________                                        Polypropylene Control                                                                         32                                                            PTFE            22                                                            Example 2       25                                                            ______________________________________                                    

The data in TABLE 4 indicate that the graft copolymer of Example 2 has asurface energy lower than the polypropylene control and approaching thatof PTFE.

180° Peel Adhesion Test:

A 2.5 cm wide, 20.3 cm long strip of pressure-sensitive adhesive tape isadhered to a 10.1 cm wide, 15.2 cm long sheet of a test substrate (apressed sample of a graft copolymer of the invention) with a free end ofthe tape extending beyond the end of the test substrate. Thetape/substrate sample is rolled twice with a 1.35 kg hard rubber rollerto ensure contact between the adhesive and the test substrate. Thesample is aged at room temperature for 24 hours. The free end of thetape is removed from the test substrate by pulling at 180° at a rate of15.2 cm/minute using a Slip/Peel Tester, (available from Instrumentors,Inc., Strongsville, Ohio).

180° Peel adhesion tests were run on pressed film samples of severalexamples and on an ungrafted polypropylene base polymer control sampleusing SCOTCH™ adhesive tape #8411 (3M) (an acrylate-basedpressure-sensitive adhesive with a 180° peel adhesion to glass of 110g/cm) and 3M adhesive tape STA-115 (a KRATON™ rubber-basedpressure-sensitive adhesive tape with a 180° peel adhesion to glass of430 g/cm). Results are shown in TABLE 5 below wherein each numberrepresents the average of five independent determinations.

                  TABLE 5                                                         ______________________________________                                                   Peel Force  Peel Force                                                        (acrylate-based)                                                   based)                 (KRATON ™                                           Example    (g/cm)      (g/cm)                                                 ______________________________________                                        Control PP 209         517                                                    1          198         330                                                    2          143         308                                                    3          154         275                                                    ______________________________________                                    

TABLE 5 indicates improvement in release properties of graft copolymersof the invention compared to the polypropylene control. Graft copolymersof Examples 1, 2, and 3 show 5%, 32%, and 26% improvement in releaseproperties for the acrylate-based adhesive tape, respectively, and 36%,40%, and 47% improvement in release properties for the KRATON™rubber-based adhesive tape.

A pressed film of the graft copolymer of Example 1 was prepared asdescribed above by pressing between PTFE-coated aluminum plates at 200°C. The film was quenched in a room temperature water bath. Samples ofthe film were then annealed in an oven at 150° C. for various times.Hexadecane contact angle and ESCA measurements were performed asdescribed above. Results are shown in TABLE 6 below.

                  TABLE 6                                                         ______________________________________                                        Annealing Time  Hexadecane                                                    (minutes)       Contact Angle (°)                                                                   F:C                                              ______________________________________                                        0               22 ± 1    0.25                                             0.5             22 ± 2    0.27                                             1.0             26 ± 3    0.24                                             2.5             32 ± 3    0.39                                             3.0             42 ± 4    --                                               5.0             40 ± 4    --                                               6.0             45 ± 3    0.45                                             8.0             47 ± 2    --                                               23.0            46 ± 2    --                                               ______________________________________                                    

The data in TABLE 6 demonstrate that annealing the graft copolymers ofthe invention at 150° C. enhances surface activity by increasing theamount of fluorochemical at the surface of the graft copolymer. The dataabove indicate an increase in fluorochemical surface activity withincreased annealing time over about 6 minutes, after which time thereappears to be little advantage gained by further annealing.

EXAMPLE 10

N-Butyl perfluorooctanesulfonamidoethyl acrylate (BuFOSEA) was graftedto polypropylene (Himont PROFAX™ PP PF-301) as described in Example 1above. The fluorochemical olefin was added to the extruder at a rate of2 mL/min (3.16 g/min) with a melt temperature of 180° C. Total flow ratewas held at about 40 g/min.

The hexadecane contact angle of the resultant graft polymer was measuredand found to be 39°. ESCA showed a F:C ratio of 0.20 on a pressed filmprepared as described in Example 1 using PTFE-coated aluminum plates.

Resistance to various solvents was also measured to determine stabilityof the surface to chemicals. 0.6 g -0.8 g samples of the pressed filmwere placed in the solutions listed in TABLE 7 below. After storage asindicated in TABLE 7, the film samples were rinsed and dried, and thepercent weight loss was determined. Hexadecane contact angles and F:Cratios were measured for each film sample.

                  TABLE 7                                                         ______________________________________                                        CHEMICAL RESISTANCE OF FLUOROCHEMICAL                                         GRAFT COPOLYMER                                                               Treatment     Wt.       Hexadecane   F:C                                      (days)        Loss (%)  Contact Angle (°)                                                                   Ratio                                    ______________________________________                                        Polypropylene Control                                                                       --        0            --                                       Control.sup.A 0%        32 ± 1    0.29                                     20% HCl (5)   3.9%      43 ± 4    0.33                                     25% H.sub.2 SO.sub.4 (5)                                                                    1.5%      42 ± 4    0.23                                     2% Chromic    1.2%      49 ± 1    0.32                                     Acid (5)                                                                      3% NaOH (5)   0.1%      35 ± 1    0.23                                     Mineral Oil (5)                                                                             5.4%      24 ± 3    0.34                                     Water (9)     0.1%      41 ± 3    0.31                                     Air (9)       0%        28 ± 3    0.45                                     Hexane (3).sup.A                                                                            2.9%      25 ± 3    0.45                                     ______________________________________                                         .sup.A Treatment at room temperature. All others are at 82° C.    

The data in TABLE 7 show that exposure to aqueous treatment decreaseshexadecane contact angle, while treatment with hydrophobic organicmaterials increases hexadecane contact angle. However, in all cases,hexadecane contact angle remains between 20° and 50° after treatment.This indicates that oil repellency is maintained, and that the graftcopolymers of the invention are resistant to chemical degradation underthe indicated conditions.

EXAMPLES 11-46

Polypropylene/BuFOSEA graft copolymers were prepared as described inExamples 1-9, above except that in Examples 11-22 only LUPERSOL™ 101initiator was used in the amounts set forth in TABLE 9; in Examples23-34 only LUPERSOL™ 130 initiator was used in the amounts set forth inTABLE 9; in Examples 35-46 a 1:1 mixture of LUPERSOL™ 101 initiator andLUPERSOL™ 130 initiator was used in the amounts set forth in TABLE 9.Screw speed was 100 rpm, and monomer flow was 2 mL/min. The percent ofgrafted fluorochemical olefin was determined using x-ray fluorescencespectrometry to determine percent fluorine. Processing conditions, i.e.,melt temperature and total flow, mole percent BuFOSEA reacted, andweight percent grafted BuFOSEA in the graft copolymers, are shown inTABLE 8.

                  TABLE 8                                                         ______________________________________                                                                Total                                                 Ex-  Initiator  Melt    Flow   Mol %                                          am-  (Conc.     Temp    (g/    BuFOSEA Wt %                                   ple  wt. %)     (°C.)                                                                          min)   Reacted BuFOSEA                                ______________________________________                                        11   L101(0.1)  180     40.9   81      6.3                                    12   L101(0.1)  200     348    70      6.4                                    13   L101(0.1)  220     36.7   79      6.8                                    14    L101(0.25)                                                                              180     30.3   78      8.1                                    15    L101(0.25)                                                                              200     40.8   89      6.9                                    16    L101(0.25)                                                                              220     39.3   86      6.9                                    17   L101(0.5)  180     40.6   91      7.1                                    18   L101(0.5)  200     42.9   88      6.5                                    19   L101(0.5)  220     46.3   86      5.9                                    20   L101(1.0)  180     45.6   92      6.4                                    21   L101(1.0)  200     38.6   90      7.2                                    22   L101(1.0)  220     53.6   95      8.9                                    23   L130(0.1)  180     42.8   88      6.5                                    24   L130(0.1)  200     46.7   96      6.5                                    25   L130(0.1)  220     45.9   100     6.9                                    26    L130(0.25)                                                                              180     41.4   93      7.1                                    27    L130(0.25)                                                                              200     41.6   86      6.5                                    28    L130(0.25)                                                                              220     47.6   88      5.8                                    29   L130(0.5)  180     29.9   75      7.9                                    30   L130(0.5)  200     43.4   93      6.8                                    31   L130(0.5)  220     43.3   99      7.2                                    32   L130(1.0)  180     39.5   98      7.8                                    33   L130(1.0)  200     24.7   70      9.0                                    34   L130(1.0)  220     43.1   86      6.3                                    35   L101/      180     36.3   63      5.5                                         L130(0.1)                                                                36   L101/      200     42.3   73      5.5                                         L130(0.1)                                                                37   L101/      220     42.0   76      5.7                                         L130(0.1)                                                                38   L101/      180     34.2   64      5.9                                         L130(0.25)                                                               39   L101/      200     49.9   94      5.9                                         L130(0.25)                                                               40   L101/      220     37.5   73      6.1                                         L130(0.25)                                                               41   L101/      180     35.8   78      6.9                                         L130(0.50)                                                               42   L101/      200     33.0   78      7.6                                         L130(0.50)                                                               43   L101/      220     35.1   74      6.7                                         L130(0.50)                                                               44   L101/      180     27.0   73      8.5                                         L130(1.0)                                                                45   L101/      200     37.7   100     8.4                                         L130(1.0)                                                                46   L101/      220     41.3   100     9.6                                         L130(1.0)                                                                Con- --         180     40      0      0                                      trol                                                                          ______________________________________                                    

Table 8 indicates that graft copolymers of this invention can be made ata wide variety of initiator concentrations. All Examples contained atleast 5.0% (by weight) BuFOSEA, and grafting efficiency was good in allExamples, ranging from 63% to 100%.

EXAMPLE 47

FIG. 3 shows a twin screw extruder much like that shown in FIG. 2 anddescribed in Examples 1-9 above. Particularly, the extruder comprises afeed zone 40, a heated barrel that comprises barrel section 42comprising both an initiation/melt zone and a monomer addition zone,barrel sections 44, 46, and 48 comprising a reaction zone, barrelsection 50 comprising a devolatilization zone and barrel section 52comprising a block zone, and a die 54. Transducer ports (e.g., T₁represents transducer number 1 in barrel section 42) are located asshown in FIG. 3, and thermocouple ports are located in each heatedsection of the extruder. The extruder was a LEISTRITZ™ Model ASF67GG.

Temperature profile of the extruder was as shown in TABLE 9 below:

                  TABLE 9                                                         ______________________________________                                               Transducer                                                                            T (°C.)                                                 ______________________________________                                               1       182                                                                   2       171                                                                   3       181                                                                   4       179                                                                   5       188                                                                   6       181                                                                   7       181                                                                   8       180                                                                   9       180                                                                   10      194                                                                   11      194                                                            ______________________________________                                    

The feed zone was ambient temperature, and screw speed was 50 rpm.

Base polymer feed hopper and extruder feed throat were purged withnitrogen. Base polymer (DYPRO™ 8771) was fed at a rate of 18.1 kg/husing a K-tron 6300 feeder. The initiator, a 1:1 mixture by weight ofLUPERSOL™ 130 initiator and LUPERSOL™ 101 initiator, was purged withnitrogen and fed at a rate of 2 mL/min using a single piston RUSKA™positive displacement pump at the downstream end of the feed throat, adistance of 270 mm from the start of the screws. BuFOSEA was purged withnitrogen and fed at a rate of 463 mL/h through a high pressure injectionvalve using a dual piston RUSKA™ positive displacement pump, at adistance of 610 mm from the start of the screws. Vacuum venting ofunreacted BuFOSEA was performed in heated barrel section 50. Productgraft copolymer was extruded through a 10-strand die that fed into awater bath and a CONAIR™ pelletizer.

EXAMPLES 48-56

Films of the graft copolymer were made as in Example 1 usingchrome-coated aluminum plates at 190° C. and a pressure of 837 mPA for30 seconds. Also, films were made by pressing the graft copolymer ofthis invention between plates that had been covered with polyimide tape(KAPTON™ Film Tape #5413, 3M) and plates that had been covered with PTFEtape (SCOTCH™ PTFE Film Tape #5490, 3M). Films of graft copolymers ofExamples 1 and 4 were also made by pressing the graft copolymer of theinvention between the chrome, polyimide, and PTFE surfaces as describedabove. Hexadecane contact angles were measured as described in Example 1above. Results are shown in TABLE 10 wherein each result is an averageof ten independent determinations.

                  TABLE 10                                                        ______________________________________                                        Polymer        Hexadecane Contact Angle (°)                            Example Sample     Chrome    Polyimide                                                                              PTFE                                    ______________________________________                                                PP Control 0         0        0                                       48      Example 1  16 ± 3                                                  49      Example 1            33 ± 2                                        50      Example 1                     49 ± 5                               51      Example 4  13 ± 2                                                  52      Example 4            29 ± 3                                        53      Example 4                     43 ± 4                               54      Example 47 19 ± 2                                                  55      Example 47           27 ± 1                                        56      Example 47                    50 ± 5                               ______________________________________                                    

The results in TABLE 10 show that the graft copolymer of Example 47exhibits surface activity similar to that of the graft copolymers ofExamples 1 and Example 4. The results in TABLE 10 also show the effectof the surface against which the graft copolymer is formed. The samplesmelted against the PTFE surface show higher surface activity than thoseformed against the more polar surfaces polyimide and chrome.

EXAMPLES 57-59

The following examples describe graft polymerization of N-ethylperfluorooctanesulfonamidoethyl acrylate (EtFOSEA) to polypropylene.Polypropylene (Amoco PP 5219, Amoco Chemical Naperville, Ill.) waspremixed with 0.25 wt % LUPERSOL™ 101 initiator, 0.25 wt % LUPERSOL™ 130initiator, and 5.0 wt % EtFOSEA. The mixture was purged with nitrogen,added in the feed zone, extruded, and collected as described inExample 1. Screw speed of the extruder was 100 rpm. TABLE 11 lists theprocess conditions for Examples 57-59.

                  TABLE 11                                                        ______________________________________                                                                Total Flow Rate                                       Example    Melt Temp. (°C.)                                                                    (g/min)                                               ______________________________________                                        57         180          40.6                                                  58         200          43.7                                                  59         220          40.5                                                  ______________________________________                                    

EXAMPLES 60-65

Films of the graft copolymers of Examples 57-59 were made as describedin Example 1 by pressing between chrome surfaces at 185° C. and 2790 mPAfor 60 seconds, and by pressing between PTFE surfaces at 174° C. and1046 mPA for 30 seconds as indicated in TABLE 12 below. Hexadecanecontact angles were measured and are shown in TABLE 12, wherein eachentry represents the average of ten independent determinations.

                  TABLE 12                                                        ______________________________________                                                           Hexadecane Contact                                                  Polymer   Angle (°)                                           Example    Sample      Chrome   PTFE                                          ______________________________________                                        --         PP Control  0        0                                             60         Example 57  25 ± 2                                              61         Example 57           65 ± 2                                     62         Example 58  24 ± 3                                              63         Example 58           69 ± 3                                     64         Example 59  31 ± 1                                              65         Example 59           71 ± 3                                     ______________________________________                                    

The data in TABLE 12 indicate that the pressed films of the inventionhave high surface activity compared to that of the polypropylenecontrol. Also, the PTFE-pressed films have a twofold or greaterhexadecane contact angle than the chrome-pressed films.

EXAMPLES 66-67

The following Examples describe the graft polymerization of N-ethylperfluorooctanesulfonamidoethyl methacrylate (EtFOSEMA) topolypropylene.

Polypropylene (Amoco PP 5219, Amoco Chemical, Naperville, Ill.)/EtFOSEMAgraft copolymers were prepared as described in Examples 1-9 above. TheEtFOSEMA was used as a 1:1 solution by weight in tetrahydrofuran, andthe solution was fed at 4 mL/min. Melt temperatures were 180° C. forExample 66 and 200° C. for Example 67. Tetrahydrofuran and unreactedmonomer were vented as in Examples 1-9. Screw speed was 60 rpm. Polymerflow rates were 38.3 (Example 66) and 42.4 (Example 67) g/min.

EXAMPLES 68-71

TABLE 13 lists the hexadecane contact angles of films prepared from thegraft copolymers of Examples 66 and 67. Results indicate improvedsurface activity compared to the control sample, and a higher surfaceactivity for the PTFE-pressed films compared to the chrome-pressedfilms.

                  TABLE 13                                                        ______________________________________                                                           Hexadecane Contact                                                  Polymer   Angle (°)                                           Example    Sample      Chrome   PTFE                                          ______________________________________                                                   PP Control  0        0                                             68         Example 66  14 ± 2                                              69         Example 66           24 ± 3                                     70         Example 67  14 ± 3                                              71         Example 67           30 ± 3                                     ______________________________________                                    

EXAMPLES 72-73

The following examples describe graft polymerization of N-allylperfluorooctanessulfonamidomethyl ethane (AlFOSME) to polypropylene(Amoco PP 5219).

These graft copolymers were prepared as in Examples 66 and 67 with melttemperatures of 180° C. (Example 72) and 200° C. (Example 73) andpolymer flow rates of 41.7 (Example 72) and 42.3 (Example 73) g/min.

EXAMPLES 74-77

TABLE 14 lists hexadecane contact angles on films of the graftcopolymers of Examples 72 and 73, prepared as in Examples 60-65. Again,increased fluorochemical surface activity compared to the control samplewas seen, and the PTFE-pressed films showed higher surface activity thanthe chrome-pressed films.

                  TABLE 14                                                        ______________________________________                                                           Hexadecane Contact                                                  Polymer   Angle (°)                                           Example    Sample      Chrome   PTFE                                          ______________________________________                                                   PP Control  0        0                                             74         Example 72  15 ± 1                                              75         Example 72           45 ± 3                                     76         Example 73  22 ± 3                                              77         Example 73           42 ± 3                                     ______________________________________                                    

EXAMPLES 78-83

The following Examples describe the preparation of fluorochemical graftcopolymers using low molecular weight base polymers. The graftcopolymers were prepared according to the general method of Examples 1-9above using a 1:1 mixture of LUPERSOL™ 101 initiator and LUPERSOL™ 130initiator as the initiator system and the components and conditionslisted in TABLE 15 below. The fluorochemical olefins were used in anamount of 10 percent by weight based on the weight of the base polymer.Initiator concentration is based on the weight of the base polymer.

The graft copolymers were extruded into film substrates of 0.1 mmthickness. ESCA analysis and 180° peel adhesion results (using the testdescribed above in connection with TABLE 5 and 3M Box Sealing Tape #371,a KRATON™ rubber-based adhesive tape with a peel strength of 610 g/cmwhen adhered to glass) are shown in TABLE 15.

The ESCA data of TABLE 15 indicate that there is more fluorine on thesurface of the films than would be expected based on the amount offluorochemical olefin used in preparing the graft copolymer. The releasedata indicate in all cases that the initial peel force of the films wassuperior to that of control base polymer.

                                      TABLE 15                                    __________________________________________________________________________                            Total            Peel Force                           Base            Fluorochemical                                                                        Initiator        (g/cm)                               Example                                                                             Polymer (MFI.sup.C)                                                                     Olefin  Concentration (%)                                                                       ESCA (% F)                                                                           Initial                                                                           Aged.sup.D                       __________________________________________________________________________    PP control                                                                          Exxon.sup.A 3085 (35)                                                                   --      --         0     500 550                              78    Exxon.sup.A 3085 (35)                                                                   EtFOSEA 1         39      80 560                              79    Exxon.sup.A 3085 (35)                                                                   EtFOSEA 0.5       47     310 460                              80    Exxon.sup.A 3085 (35)                                                                    EtFOSEMA                                                                             0.5       33     140 630                              PE control                                                                          Dow.sup.B 40060M (40)                                                                   --      --         0     160 510                              81    Dow.sup.B 40060M (40)                                                                   EtFOSEA 0.25      38      20 250                              82    Dow.sup.B 40060M (40)                                                                   EtFOSEA 0.12      22      20 170                              83    Dow.sup.B 40060M (40)                                                                    EtFOSEMA                                                                             0.25      48     190 340                              __________________________________________________________________________     .sup.A Exxon Chemical Co., Houston, TX                                        .sup.B Dow Chemical Co., Midland, MI                                          .sup.C Melt flow index                                                        .sup.D "Aged" peel force was determined using the 180° Peel Test       after heating the tape/substrate sample at 43°  C. for 11 days.   

Examples 78-80 do not have particularly durable aged peel force. In thecase of Examples 81-83, however, aged peel force was significantly lowerthan that of the control polyethylene base polymer and in the rangesuitable for commercial tape applications.

EXAMPLES 84-88

Polymer blend films were made by dry-blending 10 parts by weight of agraft copolymer of the invention with 90 parts by weight of a purematrix polymer, adding the resulting mixture to the hopper of a 11/4inch (5 cm) Killion extruder (Killion Extruders, Inc., Verona, N.J.),and extruding into a 0.1 mm thick, 15.2 cm wide film substrate under thefollowing conditions:

    ______________________________________                                        Extruder temperatures:                                                                           Zone 1    149° C.                                                      Zone 2    201° C.                                                      Zone 3    220° C.                                                      Zone 4    221° C.                                                      Neck tube 218° C.                                                      Die       218° C.                                   Extruder rpm:      25                                                         Casting roll temperature:                                                                        15° C.                                              ______________________________________                                    

Film substrates were made using the components set forth in TABLE 16below. ESCA results and 180° peel adhesion results are also shown inTABLE 16.

                  TABLE 16                                                        ______________________________________                                                Matrix     Graft     ESCA  Aged Peel                                  Example Polymer    Copolymer (% F) Force (g/cm).sup.C                         ______________________________________                                        PE control                                                                            Dow.sup.A 6806                                                                           --         0    540                                        84      Dow.sup.A 6806                                                                           Example 81                                                                              15    400                                        PP control                                                                            Fina.sup.B 3374X                                                                         --         0    580                                        85      Fina.sup.B 3374X                                                                         Example 83                                                                              17    260                                        86      Fina.sup.B 3374X                                                                         Example 79                                                                              23    340                                        87      Fina.sup.B 3374X                                                                         Example 78                                                                              18    220                                        88      Fina.sup.B 3374X                                                                         Example 82                                                                              14    260                                        ______________________________________                                         .sup.A Dow Chemical Co., Midland, MI                                          .sup.B Fina Chemical Co.                                                      .sup.C "Aged" peel force was determined using the 180° Peel Test       set forth in Examples 1-9 above (3M adhesive tape STA115) after heating       the tape/substrate sample at 43° C. for 11 days.                  

The ESCA data of Table 16 indicate that there is more fluorine on thesurface of the films than would be expected based on the amount of graftcopolymer used in preparing the blend. The release data indicate in allcases the aged peel force of the blend is lower than that of the controlbase polymer and in the range suitable for commercial tape applications.

Various modifications and alterations of this invention will becomeapparent to those skilled in the art without departing from the scopeand spirit of this invention, and it should be understood that thisinvention is not to be unduly limited to the embodiments set forthherein.

We claim:
 1. A fluorochemical graft copolymer comprising: a base polymercomprising polymerized units derived from monomers having terminalolefinic double bonds, having grafted thereto a moiety of the formula

    --CH.sub.2 --CHR--Q--R.sub.f

wherein R is hydrogen, trifluoromethyl, or lower alkyl; Q is a divalentlinking group that does not substantially interfere with free radicalpolymerization; and R_(f) is a fluoroaliphatic group comprising a fullyfluorinated terminal group containing at least seven fluorine atoms. 2.A graft copolymer according to claim 1, wherein the base polymer isselected from the group consisting of polymethyl methacrylate,poly-4-methylpentene, polypropylene, polybutylene, polystyrene,polyethylene, polybutadiene, ethylene/vinyl acetate copolymer,ethylene/butyl acrylate copolymer, and mixtures and blends thereof.
 3. Agraft copolymer according to claim 1, wherein the grafted moiety is afluorochemical olefin of the formula C₈ F₁₇ SO₂ N(C₄ H₉)CH₂ CH₂OC(O)CH═CH₂.
 4. A graft copolymer according to claim 1, wherein thegrafted moiety is a fluorochemical olefin of the formula C₈ F₁₇ SO₂ N(C₂H₅)CH₂ CH₂ OC(O)CH═CH₂.
 5. A graft copolymer according to claim 1,wherein the grafted moiety is a fluorochemical olefin of the formula C₈F₁₇ SO₂ N(C₂ H₅)CH₂ CH═CH₂.
 6. A graft copolymer according to claim 1,wherein the grafted moiety is a fluorochemical olefin of the formula C₈F₁₇ SO₂ N(C₂ H₅)CH₂ CH₂ OC(O)C(CH₃)═CH₂.
 7. A graft copolymer accordingto claim 1, wherein the base polymer is a low molecular weightpolyolefin.
 8. A graft copolymer according to claim 7, wherein the basepolymer has a melt index of at least about 20 and up to about 500.